Resin based dental restorative materials are becoming the material of choice by dentists and patients due to their desirable aesthetic properties. However, gap formation occurs between the restorative material and tooth structure as a result of inadequate adhesive bonding, polymerization shrinkage stress, thermal stress, and mechanical stress (mastication force). This leads to microleakage and, subsequently, secondary caries.
A restorative material that possesses antibacterial properties and inhibits bacterial growth around the restoration would be desirable. Various antibacterial agents have been incorporated into oral products such as rinse solutions, toothpastes, coatings, and dental restorative compositions to kill bacteria or inhibit bacterial growth. Those antibacterial agents include phenols/essential oils (U.S. Pat. Nos. 5,260,062 and 6,326,417), quaternary ammonium compounds (U.S. Pat. Nos. 4,820,507; 5,330,746; and 6,355,704), and metal salts containing zinc (U.S. Pat. No. 4,522,806).
Silver has been shown to be an effective antibacterial agent. For example, U.S. Pat. No. 5,340,850 discloses a method to physically implant silver ions onto the surface of an inorganic filler or into a resin matrix using a special ion implantation apparatus. U.S. Pat. No. 6,379,712 discloses a nanosilver-containing antibacterial granule comprising a metallic silver core surrounded by silver oxide, obtained by precipitating silver from solution onto cut stalk marrow, and grinding the nanosilver-containing stalk marrow. U.S. Pat. No. 6,267,590 discloses an orthodontic dental bracket and arch wire coated with an antimicrobial polymeric coating composition comprising a zeolite particle containing silver ions. U.S. Pat. No. 4,911,898 discloses preparation of zeolite particles containing silver ions having antibacterial properties, prepared by doping the zeolite particle with silver ions through ion-exchange in a silver-ion-containing aqueous solution.
None of the aforementioned references disclose a dental composition containing ethylenically unsaturated monomers and polymerization initiators in which a silver-containing ceramic provides desirable properties, such as antimicrobial properties and color stabilization, without sacrificing the mechanical strength of the dental composition.